The invention is related generally to vial access devices of the type used in the transfer of medical fluids between a vial and another medical fluid container, and more particularly, to sealed vial access devices providing a closed system to avoid the formation of aerosols escaping to the outside atmosphere.
Many medicaments are prepared, stored, and supplied in dry or lyophilized form in glass vials. Such medicaments must be reconstituted at the time of use by the addition of a diluent thereto. Many pharmaceutical products supplied in glass vials have a closure that can be penetrated by a syringe so as to add or subtract material from the container. For example, often times, medicines are supplied in dry form inside a vial having a rubber closure or stopper. Liquid such as deionized water is added to the vial to dissolve or suspend the solid material. Sometimes, serum and other medicines are freeze dried in the vial and are then reconstituted in the vial. Various methods of adding the diluent to the dry or lyophilized medicament have been used over the years. One method that is commonly used is the vial access device technique wherein a cannula is inserted at the vial access device through the vial stopper and then attaching a bottle or a syringe that contains the diluent to the vial access device. Once the diluent container is connected, the diluent is communicated to the dry or lyophilized medicament residing in the vial resulting in reconstitution of the medication in liquid form. After reconstitution, the liquid is usually withdrawn from the vial into the intravenous solution bottle or syringe, or other container for administration to the patient through an intravenous (“IV”) administration set or by other means.
Vials made of glass or polymeric materials, the walls of which are non-collapsible, require an air inlet when medical fluid is withdrawn to prevent the formation of a partial vacuum in the vial. Such a partial vacuum inhibits fluid withdrawal from the vial. Typically, adapters for use with such vials have a sharpened cannula that includes both a medicament fluid lumen and a vent lumen therein. The vent lumen may provide pressure equalization when fluid is added to the vial or is withdrawn from the vial so that such fluid movement occurs smoothly.
Access ports for injecting fluid into or removing fluid from a container, such as a drug vial, are well known and widely used. Conventional seals of drug vials generally involve a pierceable rubber stopper formed of an elastomeric material such as butyl rubber or the like, placed in the opening of the vial. A closure, typically formed of metal, is crimped over the rubber stopper and the flange of the vial to positively hold the stopper in place in the opening of the vial. The closure has an outer size, known as a “finish size.” A sharp cannula is inserted through the rubber stopper to position the distal, open end of the cannula past the rubber stopper to establish fluid connection with the interior of the vial. In the case of certain medications, such as those used for chemotherapy or nuclear medicine, the rubber stopper is made thicker so that increased protection is provided against leakage.
Vial access devices have been found useful in that their sharpened cannula is used to pierce the stopper and move far enough into the vial interior to establish fluid communication between the vial and the connection device of another fluid container or fluid conduction device. For example, the adapter may include a female Luer fitting opposite the sharpened cannula to receive the male luer of a syringe. The “adapter” therefore adapts the vial to the syringe, or adapts the sharpened cannula to the male luer of the syringe.
It has also been found useful in some applications to provide a means to attach or anchor the adapter to the vial to hold it in place while fluid communication between the vial and another device proceeds so that inadvertent disengagement of the adapter from the vial does not occur. For example, the adapter may have arms that engage the neck or flange of the vial and hold the adapter in place on the vial. Other means include a circular slotted housing that fits around the outside of the vial closure and snaps onto the vial closure under the crimped retaining cap on the under-surface of the vial's flange thereby grasping the vial neck flange and the underside of the closure. The circular housing typically has a plurality of claws or other retaining devices that are positioned under the flange of the vial opening thereby interfering with removal of the adapter from the vial.
When an ordinary container and closure is used to dispense medicines which have been reconstituted, several problems are created. Normally when a liquid is added to a powder in a vial there is an increased pressure in the container and syringe due to the change in volume. This pressure tends to force a discharge of the liquid through an opening formed by the closure puncture and the hypodermic needle point, either when the needle is withdrawn or later when a needle is inserted to withdraw some of the contents.
Another difficulty arises when the powders and the newly formed liquids experience aerosoling. This phenomenon occurs when small particles or droplets, either powder or in the liquid state, become airborne during the turbulence caused from the pressure released during withdrawal or insertion of the needle into the container. Thus, these airborne particles escape from the container and may contact the healthcare worker.
Advances in modern medicine have made the aerosoling problem and others as described above much more serious. Specifically, during the treatment of cancer, chemotherapy drugs are packaged in glass vials in a freeze dried form and are thereafter reconstituted at the time when treatment is beginning. Various quantities of the reconstituted liquid are withdrawn over a period of time using syringes. Because cancer treating drugs are often times powerful, sometimes causing retardation or stoppage of all cell growth, it is obviously an advantage to avoid having unnecessary contact. Every effort is made to avoid contact by the preparer and dispenser of chemotherapy drugs. Not only cancer treating materials are of concern. As AIDS and AIDS-related diseases are treated, drugs which are used may not be safe for universal contact. Antibiotics and cloning drugs also need to be carefully monitored.
For such reconstitution activities, a vented vial access device is used to avoid any difficulties with a partial vacuum or high pressure inside the vial. These are sometimes known as pressure-equalizing vial access devices. However, with some vented vial access devices this technique is unsatisfactory because both the dry or lyophilized material and the diluent can be exposed to ambient airborne bacterial contamination during withdrawal of the reconstituted medical fluid if a filter is not present in the vial access device.
During the reconstitution process of certain medical fluids, such as chemotherapy fluids or nuclear medicines, it is also desirable to avoid contamination of the surrounding air resulting from the formation of aerosols or drops in the vial. As used herein, aerosols are suspensions of solid or liquid particles in a gas, such as air. Contamination is possible during the injection of the diluent into the vial because more material is being added to the closed space of the vial and therefore, the vent of the adapter must channel away an equal amount of air from the vial to make room for the additive. If this air removed from the vial is channeled to the outside atmosphere, such contamination can lead to problems, among other things, in the form of allergic reactions in the exposed personnel, especially when the air is contaminated with cytotoxic drugs, chemotherapeutic drugs, anesthetics, media containing isotopes, and allergy inducing substances of various kinds.
Traditionally, drugs are aspirated from vials having rigid walls by the following process:                a. the user aspirates a volume of air into a syringe that is equal to the volume of drug to be removed from a vial;        b. the user pierces the top of the drug vial with a needle that is attached to the syringe;        c. the user depresses the plunger on the syringe, injecting the air from the syringe into the vial which causes an increase in pressure within the vial; and        d. a volume of drug is aspirated from the vial, allowing the pressure within the vial to drop back to near atmospheric pressure.        
If the vial is accessed more than once in this manner and the volume of air that is injected is slightly more than the volume of drug that is removed, the pressure within the vial will gradually increase. If the pressure becomes too high, some drug may spray from the needle hole in the vial closure as the needle is removed. If the drug contained in the vial is toxic, it may harm anyone who then contacts the loose drug.
Chemotherapy pins are frequently used to aspirate chemotherapy drugs from vials. Chemo pins contain a hydrophobic membrane and filter that act as a barrier between the drug and outside atmosphere. This barrier allows air to enter and exit the vial as drug is removed while preventing liquid from escaping and filtering the gases that pass through it. This prevents the buildup of pressure within the vial as described above. However, many nurses and pharmacists do not trust that the filter prevents all harmful vapors from escaping the vial and reaching the atmosphere. Therefore, most users are required to use the chemo pin under a vent hood within the pharmacy.
Prior approaches provide a sealed or closed system. However, problems have persisted. For example, one system is attached to a drug vial and then a syringe is used to prime the vial with a volume of air equal to the volume of fluid that will be withdrawn from the vial. The approach uses a thin, flexible section that is in fluid communication with the syringe and the vial. The thin, flexible section expands outward as the syringe is used to force air into the vial, preventing an increase in gas pressure within the vial. Then as fluid is removed from the vial, the flexible section collapses, preventing a decrease in pressure (vacuum) within the vial. However, the thin, flexible section expands outward making it vulnerable to rupture if it contacts a sharp object. Also, if over inflated, it may likewise rupture. Additionally, if the user forgets to prime the vial with air before aspirating the drug, a vacuum will develop within the vial which will inhibit the withdrawal of fluid from the vial.
Hence, those skilled in the art have recognized a need for a pressure-equalizing vial access device having improved aerosol retention capability so that reconstituted contents of the vial that become aerosolized do not escape the vial to the atmosphere. The present invention fulfills these needs and others.